초록 ▼

A method of controlling a vehicle hydraulic drive system of the type including a plurality of fluid pressure actuated wheel motors (13,15) connected in a parallel circuit with a source (17) of pressure. A flow restrictor valve (65) is disposed in a downstream conduit (27) of each of the wheel motors

A method of controlling a vehicle hydraulic drive system of the type including a plurality of fluid pressure actuated wheel motors (13,15) connected in a parallel circuit with a source (17) of pressure. A flow restrictor valve (65) is disposed in a downstream conduit (27) of each of the wheel motors (13,15). The method involves determining the theoretical fluid flow for each motor, the actual fluid flow through each motor, and generating an error signal (107) which is then used to bias the restrictor valve (65) toward a flow restriction position. The disclosed method can be used to achieve steering at greater than kinematic, by scrubbing the inside front wheel, or can be used to prevent wheel slip of propulsion wheels, or can be used to prevent scrubbing of a wheel during hydrostatic braking, or can even be used to achieve vehicle steering.

대표청구항 ▼

[ What is claimed is:] [8.] A vehicle hydraulic drive system for driving a pair of driven wheels of a steerable vehicle, said drive system being of the type comprising a source of pressurized fluid, and a fluid pressure actuated motor operable to drive each of said driven wheels at varying speeds in

[ What is claimed is:] [8.] A vehicle hydraulic drive system for driving a pair of driven wheels of a steerable vehicle, said drive system being of the type comprising a source of pressurized fluid, and a fluid pressure actuated motor operable to drive each of said driven wheels at varying speeds in response to varying rates of fluid flow to said motor from said fluid source, said motors being connected in a parallel circuit with said fluid source; a source of control fluid pressure; each of said motors including an inlet conduit disposed upstream of said motor, and an outlet conduit disposed downstream of said motor when the vehicle is moving in a normal forward direction, characterized by:(a) each of said motors having a control system including a proportional flow restrictor valve disposed in said outlet conduit, and a pressure reducing valve disposed in said inlet conduit;(b) pilot valve means in fluid communication with said source of control fluid pressure and operable to generate a pilot signal whenever at least a predetermined, minimum turning of the vehicle occurs; and(c) said pilot signal being operable to bias said pressure reducing valve from a normal position, providing a general pressure drop toward a pressure reducing position, and to bias said proportional flow restrictor valve from a normal position, providing generally unrestricted flow toward a flow restriction position.